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<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <script src="./js/Itcast.core.js"></script>
    <script src="./js/itcast.ctor.js"></script>
    <script src="./js/Itcast.dom.js"></script>
    <script src="./js/Itcast.event.js"></script>
    <script SRC="./js/Itcast.style.js"></script>
    <script>
        Itcast.fn.extend({
            attr: function ( name, value ) {
                if  ( value === undefined ) {
                    return this[ 0 ].getAttribute( name );
                } else {
                    return this.each( function () {
                        this.setAttribute( name, value );
                    });
                }
            }


        })

    </script>
</head>
<body>
    
</body>
<script>

    I( '<img />' )
    .appendTo( 'body' )
    .attr( 'src', 'https://ss1.baidu.com/9vo3dSag_xI4khGko9WTAnF6hhy/image/h%3D300/sign=8c56d4a6d8c8a786a12a4c0e5708c9c7/5bafa40f4bfbfbed022d422371f0f736afc31f71.jpg' );


    // alert( I( 'img' ).attr( 'src' ) );
</script>
</html>